1. Field of the Invention
The invention relates to methods of purifying phenol, and more particularly to the removal of acid contaminants from phenol using anionic exchange resins.
2. Brief Description of the Related Art
Phenol is a starting reactant for the synthesis of a wide variety of chemical compounds including, for example, bisphenol-A. In the synthesis of such compounds, purity of the phenol is generally a concern. For example, in the synthesis of bisphenol-A, contaminant acid compounds present in association with the phenol can have an adverse effect when carried into the product bisphenol-A (high temperature cracking of the bisphenol-A). The contaminants can catalyze numerous side reactions and degrade the desired product.
The use of anionic exchange resins to remove acidic contaminants from phenol-containing process streams has been described previously. For example, European Patent Application 0 329 075 published Aug. 23, 1989 (Mitsui Toatsu Chemicals, Inc.) describes bisphenol-A product streams containing residual phenol reactant and acid contaminants. The product stream is treated with weakly basic ion-exchange resins to remove the acid contaminants before separating the desired bisphenol-A by distillation. A similar treatment of bisphenol-A product streams is described in U.S. Pat. No. 4,766,254 (Faler et al.).
The present invention is concerned with purity of phenol as a starting material in organic synthesis and not with the treatment of other products which may be contaminated with phenol, i.e.; the phenol being present only as a contaminant itself.